New York Laws
Part 2 - Form, Formation and Readjustment of Contract
2-208 - Course of Performance or Practical Construction.

(1) Where the contract for sale involves repeated occasions for
performance by either party with knowledge of the nature of the
performance and opportunity for objection to it by the other, any course
of performance accepted or acquiesced in without objection shall be
relevant to determine the meaning of the agreement.
(2) The express terms of the agreement and any such course of
performance, as well as any course of dealing and usage of trade, shall
be construed whenever reasonable as consistent with each other; but when
such construction is unreasonable, express terms shall control course of
performance and course of performance shall control both course of
dealing and usage of trade (Section 1--205).
(3) Subject to the provisions of the next section on modification and
waiver, such course of performance shall be relevant to show a waiver or
modification of any term inconsistent with such course of performance.

Structure New York Laws